I think brush/grill guards, generally speaking, have nowhere near the utility of a well built and engineered bumper/gaurd combo. Bolt on brush/grill guards attach to factory supplied bumpers. Many times they stick out in front of or hang under the bumper. This diminishes clearence and approach angle. Due to the available attachment points and design of the outer light gaurds, ability to absorb frontal impact without collapsing onto the body is less than that of a reasonably well engineered aftermarket bumper/front end gaurd.
Third gen Montero aftermarket choices may be limited. I understand your trepidation with ARB, while offering better than OEM front end protection, they are noted to "fold up" by users that have experienced front impacts. ARB Bullbars have the "ExPo/Overlander" look and label that gains you currency in this community but several products in the same price range can net greater strength and protection.
Perhaps a simple light bar, that doesn't rob you of clearence is the best choice if your only concern is mounting aux lights?